1. Bases Curriculares para la Educación Básica (Curricular Bases for Elementary School);Ministerio de Educación de Chile,2012
2. Real Decreto 157/2022, de 1 de marzo, por el que se Establecen la Ordenación y las Enseñanzas Mínimas de la Educación Primaria (Royal Decree 157/2022, of March 1, which Establishes the Organization and Minimum Teachings of Primary Education);Boletín Oficial del Estado (BOE),2022
3. Common Core State Standards Mathematics;Common Core State Standards Initiative (CCSSI),2010
4. The Ontario Curriculum Grades 1–8: Mathematics;Ontario Ministry of Education and Training,2020
5. Meanings Attributed to Letters in Functional Contexts by Primary School Students